1. Field of the Invention
The present invention is generally concerned with clutches and is more particularly directed to those designed to be fitted to automobile vehicles.
2. Description of the Prior Art
As is known, a clutch of this kind generally comprises a first plate, called the reaction plate or flywheel, which is designed to be constrained to rotate with a first shaft, in general a driving shaft, in practice the motor output shaft in the case of an automobile vehicle, a friction disk which is designed to be constrained to rotate with a second shaft, in general a driven shaft, in practice the input shaft of the gearbox in the case of an automobile vehicle, a second plate called the pressure plate constrained to rotate with the reaction plate and mounted axially mobile relative to the latter, axially acting elastic means adapted to urge the pressure plate towards the reaction plate in order to clamp the latter and thus engage the clutch, and bearing means which, fast with the reaction plate in the axial direction, provide axial bearing support to said axially acting elastic means.
At present, the axially acting elastic means are more often that not formed by the circumferentially continuous part, forming a Belleville spring, of a generally annular part commonly called the diaphragm spring, the central part of which is to this end divided into radial fingers by slots and conjointly forms means adapted to command disengagement of the clutch when acted on by a control member, commonly called the clutch release bearing, itself governed by a control available to the user.
More often that not the bearing means associated with the axially acting elastic means are themselves formed by a generally annular and circumferentially continuous part commonly called the cover.
This applies both when, in order to command disengagement of the clutch, the control member associated with the diaphragm spring must push on the latter, that is to say operate in the axial direction towards the reaction plate and when, in order to command such disengagement, the control member associated with the diaphragm spring must pull on the latter, that is to say operate in the axial direction away from the reaction plate, although in this case the diaphragm spring is not necessarily fastened to the cover in such a way that it can flex, but merely bears against the latter, so that the cover may be reduced to a ring, as in the clutch described in French Pat. No. 1 422 552.
At present it is generally accepted that, for it to operate under good conditions, the diaphragm spring must be substantially continuously supported in the circumferential direction on the bearing means associated with it for this purpose.
The present invention is based on the initially surprising observation that, contradicting this received wisdom, it is possible that advantage to provide non-continuous bearing support for the diaphragm spring.